TERRORISM, HARDLY a sudden crisis of the mid-1980s, has been a fact of life for decades. The situation certainly isn't getting any better, but it isn't getting much worse, either. Tough antiterrorism measures may help curb the problem, but probably not very long or very much.

That's the analytical picture that emerges from statistics on terrorism compiled by the State Department's Office for Counter-Terrorism and Emergency Plannning and the Federal Aviation Administration. The good news is that the United States isn't facing a new or unique threat from terrorism; the bad news is that terrorism is a serious problem and is likely to remain so as long as there are people in the world with grievances and access to weapons.

The statistics don't capture some changes, like the growing sponsorship of terrorism by such nations as Libya, Syria and Iran. But it's likely that the most profound change isn't in the nature or frequency of terrorism, but in our perception of it. Thanks largely to television, the terrorism war has entered our living rooms.

Consider some of the surprising statistical findings:

*The terrorism danger to Americans hasn't increased significantly compared to the early 1970s. More Americans died in terrorist incidents in 1974 (42) than last year (23), and more Americans died in 1972 (23) than in 1984 (11), according to the State Department statistics.

*The Middle East isn't the leading venue for terrorist attacks involving Americans; the real hotspots are Latin America and Europe. There were 369 terrorism incidents involving Americans in Latin America from 1980 to 1985 and 458 in western Europe, compared with only 84 in the Middle East. Moreover, in all but three of the past 18 years, Latin America had more terrorism incidents involving Americans than the Middle East; Europe had more such incidents than the Middle East every year but one. (The geographical lines are blurred, to be sure, by the fact that a Libyan terrorist can operate as easily in Paris as in Cairo.)

*American diplomats and military personnel aren't the main targets of terrorists; businessmen are. From 1981 to 1985, there were more attacks each year against U.S. business representatives than diplomats. In every year but one during that period, there were more incidents involving American business people than military personnel.

*Bomb explosions aboard commercial aircraft aren't a new problem; they have been a continuous danger since the advent of international air travel. Indeed, FAA statistics show that the threat of mid-air explosions has been declining slightly in recent years. FAA statistics show that during the 1970s, there were 44 incidents in which bombs exploded aboard airplanes; from 1980 to 1984, there were only 11 such incidents. The death toll from such bombings during the 1970s was 650; the death toll from 1980 through 1984 was 115.

The number of international terrorist bombings around the world has been fairly constant over the past 18 years. There were 404 bombings last year, according to the State Department -- high, but still less than the 452 recorded in 1972. In every year since 1969, there have been at least 120 terrorist bombings, and in most of those years there have been over 200 bombings.

*Terrorism takes a much higher toll among non-Americans than Americans. Last year, international terrorism produced 2,223 casualties, of which only 162 were Americans. During the last five years, Americans have accounted for less than 10 percent of the total 7,260 casualties attributable to international terrorism.

The State Department statistics on "international" terrorism include only incidents that involve citizens or territory of more than one country. Thus, they don't measure the growth of strictly internal political violence.

A broader calculation used by Risks International Inc., a consulting group based in Alexandria, Va., shows a steeper increase in terrorism, from 293 incidents in 1970 to 3,525 in 1984. But even their numbers show a slight drop last year, to 3,010.

The statistics paint a depressing picture of the havoc wrought by terrorists and the diversity of causes invoked by them. The numbers also show that while Mideast terrorism has tended to get the headlines over the past two decades, the terrorism problem is global.

Take the problem of aircraft explosions. The FAA has recorded 80 such incidents aboard commercial aircraft since 1949. The nationality of the aircraft that were bombed gives some idea of the range of asserted causes: 22 American planes, eight from the Philippines, six French, four British, four from South Vietnam, two from South Yemen, two from India, two from Ethiopia, two from Switzerland, and so on.

A State Department report titled "Patterns of Global Terrorism: 1984," tells the same story of a world bursting with terrorist grievances, some of them dating back centuries. A chronology of "significant terrorist events" for that year lists 47 incidents; of this total, 19 incidents in Europe and the Mideast appeared to involve Arab terrorists. The rest represented the range of global extremism: Irish provos, Spanish antifascists, Namibian guerrillas, Peruvian leftists, Indian Sikhs, Belgian communists and Sri Lankan separatists.

If this mass of statistical evidence offers any lesson, it's that the United States shouldn't look for any quick fixes to the terrorism problem. We may succeed, through good intelligence and a policy of reprisal, in putting out today's terrorism fire in Libya or Iran, and that's all to the good.

But recent history teaches that the fire is likely to erupt somewhere else before long. And in this long and frustrating struggle, the best weapons are likely to be patience, resolve and common sense.